1. Field of the Invention
The present invention relates to a driving device, an image reading apparatus and an image forming apparatus, and more specifically, a driving device which reciprocates a scanning unit for reading an image on an original put on an original platen, an image reading apparatus and an image forming apparatus each provided with the driving device.
2. Description of Related Art
An example of an image reading apparatus which is provided with such a kind of conventional driving device is disclosed in Japanese Patent Application Laying-open No. H11-215320 [H04N 1/04, G03B 27/50] (Patent Literature 1) laid-open on Aug. 6, 1999. The driving device of Patent Literature 1 comprises a transmission timing belt (pull member) for transmitting driving force of a driving pulley to a reading unit (scanning unit) for reading image information and a tension pulley (following pulley) for applying tension to the transmission timing belt. Then, the tension pulley is supported rotatably by a tension pulley stand (pulley holder) which is fixed to a guide rail.
However, when assembling the driving device of Patent Literature 1, since the following pulley is fixed to the pulley holder with screws or the like, and the pulley holder is secured to the guide rail with screws or the like while giving tension to the pull member, a fastening work (assembling work) of the screws is troublesome. Furthermore, when the following pulley is to be exchanged, similarly, a work for removing and fastening of screws is required, and therefore, an exchanging work of the following pulley takes time and effort.